The computer mainframe emits sounds similar to those of an electric drill
Open the box, you will find it very obvious one is the fan, then you should see the CPU fan, the boot, see when the fans turn up, make noise when you are being pressed by hand rotating fan, remember do not use a hand to touch the fan page. Then put your hand to break, when light is off, fan fan page, if you hold down the fan, it is found that the noise disappeared, CPU fan, in turn, note: the power supply fan is not good at, unless the demolition of power supply, suggested that the fan CPU and graphics card test finished, then judge!
Well, your question, obviously is the fan bearing after long time rotating wear badly, you must be the morning boot, shutdown for a night, because now the autumn temperature is low, according to the principle of thermal expansion and contraction, the boot time of the morning, because of your fan bearing wear and thermal expansion and contraction that makes itself the fan bearing wear relative matter, this is brought together, will send out the sound of the friction ~ and then restart, because before your fan is turned, the heat generated bearing expansion, so there is no sound, this kind of problem, often there are written users in a year the cold area and computer!
This is quite normal, the fan inside the chassis, there are generally 3, power fan, CPU fan, video card fan. These fans, the speed is basically the speed of 1000 revolutions per minute, just imagine, if it is a platoon fan at this rate, 6 years, it is estimated scrapped
